Distance mapping or depth mapping cameras have become ubiquitous in numerous fields such as robotics, machine vision for acquiring three-dimensional (3D) information about objects, intelligent transport systems for assisting driver safety and navigation, bioscience for detecting 3D laparoscopic images of internal organs, non-contact fingerprinting, and image manipulation in movie or television studios.
To achieve the goal of distance mapping an object in order to acquire its 3D information, numerous methods have been developed. The triangulation method uses two or more images taken by strategically placed cameras to calculate the position of the target object. The 3D information is obtained by synchronizing the movement of the light projection spot with the direction of the return path of the light scattered to the detector. This triangulation method is limited in that it is too slow and generally can not provide for the real-time operation of a television camera.
The time of flight method makes use of the time required for a round trip of a laser beam using a phase or frequency modulated probe light. A heterodyne detection converts the phase or frequency information into the distance to the target object. While depth resolution can be within micrometers, time of flight methods can be limited to the order of minutes in providing a depth map of a target object.
Projection methods determine depth information from the patterns of configured light projected onto a target object. The best known projection method is the moiré technique. The moiré technique incorporates two grid patterns projected before and after the surface distortion to generate a moiré pattern of the deformed surface. While a moiré pattern can be readily generated, not so are the corresponding distance calculations. This distance is calculated in a manner similar to applying triangulation at every intersection of the pattern.
The AXI-VISION CAMERA™ method as described in U.S. Pat. No. 7,0165,519 B1 is based on a hybrid of the projection and time of flight methods. The projecting light is temporally rather than spatially modulated. To acquire the depth pattern, an instantaneous time of flight pattern is captured using an ultra-fast shutter. Distance is then calculated at every pixel providing a picture quality to that of High Definition Television (HDTV). To achieve its results, the AXI-VISION CAMERA™ method requires a large number of fast response time LEDs, a photomultiplier based shutter that are all secured to the AXI-VISION CAMERA™.
The object of the present invention is to provide a method and device for detecting and mapping three-dimensional information pertaining to one or more target objects while further addressing the limitations of the prior art.